/*
 *  Copyright:  (C) 2018 LingYun IoT System Studio
 *              All rights reserved.
 *
 *  File name:  thread_lock.c
 *Description:  The code changes according to Thread. c to solve the problem 
 *              of sharing resources through the mechanism of locking.
 *
 *    Version:  1.1
 *     Author:  Guo Wenxue <guowenxue@gmail.com>
 *		        Copied by Zhu Tianyin <zhuty_cn@163.com>
 *  ChangeLog:  1.0  Release initial version in 2018.
 *              1.1  Copy and change some details on "02/01/2021".
 */
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>

void *thread_worker1(void *args);
void *thread_worker2(void *args);

typedef struct worker_ctx_s
{
    int             shared_var;
    pthread_mutex_t lock;
}worker_ctx_t;

int main(int argc, char **argv)
{
    worker_ctx_t    worker_ctx;
    pthread_t       tid;
    pthread_attr_t  thread_attr;

    worker_ctx.shared_var = 1000;
    pthread_mutex_init(&worker_ctx.lock, NULL);

    if( pthread_attr_init(&thread_attr) )
    {
        printf("pthread_attr_init() failure: %s\n", strerror(errno));
        return -1;
    }

    if( pthread_attr_setstacksize(&thread_attr, 120*1024) )
    {
        printf("pthread_attr_setstacksize() failure: %s\n",strerror(errno));
        return -1;
    }

    if( pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED) )
    {
        printf("pthread_attr_setdetachstate() failure: %s\n", strerror(errno));
        return -1;
    }

    pthread_create(&tid, &thread_attr, thread_worker1, &worker_ctx);
    printf("Thread worker1 tid[%ld] created ok\n", tid);

    pthread_create(&tid, &thread_attr, thread_worker2, &worker_ctx);
    printf("Thread worker2 tid[%ld] created ok\n", tid);

    while(1)
    {
        printf("Main/Control thread shared_var: %d\n", worker_ctx.shared_var);
        sleep(10);
    }
    pthread_mutex_destroy(&worker_ctx.lock);
}

void *thread_worker1(void *args)
{
    worker_ctx_t    *ctx = (worker_ctx_t *)args;

    if( !args )
    {
        printf("%s() get invalid arguments\n", __FUNCTION__);
        pthread_exit(NULL);
    }
    printf("Thread worker1 [%ld] start running...\n", pthread_self());

    while(1)
    {
        pthread_mutex_lock(&ctx->lock);

        printf("+++: %s before shared_var++: %d\n", __FUNCTION__, ctx->shared_var);
        ctx->shared_var ++;
        sleep(2);
        printf("+++: %s after sleep shared_var: %d\n", __FUNCTION__, ctx->shared_var);

        pthread_mutex_unlock(&ctx->lock);

        sleep(1);
    }
    printf("Thread worker1 exit...\n");

    return NULL;
}

void *thread_worker2(void *args)
{
    worker_ctx_t    *ctx = (worker_ctx_t *)args;

    if( !args )
    {
        printf("%s() get invalid arguments\n", __FUNCTION__);
        pthread_exit(NULL);
    }
    printf("Thread worker2 [%ld] start running...\n", pthread_self());

    while(1)
    {
        if( 0 != pthread_mutex_trylock(&ctx->lock))
        {
            continue;
        }
        printf("---: %s before shared_var++: %d\n", __FUNCTION__, ctx->shared_var);
        ctx->shared_var ++;
        sleep(2);
        printf("---: %s after sleep shared_var: %d\n", __FUNCTION__, ctx->shared_var);

        pthread_mutex_unlock(&ctx->lock);

        sleep(1);
    }
    printf("Thread worker2 exit...\n");

    return NULL;
}